The present invention relates to a thin film magnetic head used for a magnetic disk unit, and in particular, to an induction type thin film magnetic head as a recording head.
Recently, in magnetic heads used for magnetic disk units, high density and high efficiency of recording media have been pursued, and miniaturization and high accuracy in shape of the heads have been promoted.
In order to cope with these requirements, a thin film magnetic head is required to have a large magnetic field at a point of a magnetic pole that contributes to magnetic recording, and the narrowing and high accuracy of a track width. In order to solve this problem, various examinations have been performed, that is, high Bs material has been adopted for a magnetic pole edge so as to enlarge a magnetic field of a thin film magnetic head, and head structure has been improved so as to improve the accuracy of the track width. One structure of a thin film magnetic head by the prior art is shown in FIG. 6. In the magnetic head with the structure in FIG. 6, it is intended to decrease the influence of a step of a coil 9 and non-magnetic insulating film 10 to an upper magnetic edge layer 7 that defines the track width by separately forming a magnetic core in an upper portion from a gap 4 to achieve the narrowing and high accuracy of the track width.
Nevertheless, even in the thin film magnetic head with the structure shown in FIG. 6, it becomes difficult to accurately form the upper magnetic edge layer 7 and a lower magnetic edge layer 1 in predetermined track width.
In addition, as the narrowing of track width and the high coercivity of a medium has been advanced, a recording magnetic field that has been required for a recording head has become large.
In order to improve the recording magnetic field of a recording head, it is effective to bring a track width spreading position Ly of the upper magnetic edge layer 7, which is shown in FIG. 6 as 20, closer to the side of an ABS 30 as a flying surface. However, in this case, although the magnetic field is improved, there is a possibility that effect track width may become large since a leakage magnetic field toward the track width also becomes larger. In addition, there is a non-magnetic insulating film 13 that defines gap depth Gd as 40 in the head structure in FIG. 6, and this non-magnetic insulating film 13 has a step of about 1 μm or so. Since the upper magnetic edge layer 7 that defines the track width is formed on the non-magnetic insulating film 13, there is a possibility that the accuracy of the resist pattern that forms the upper magnetic edge layer 7 is deteriorated because of being affected by a resist film thickness distribution and halation as the track width becomes narrower.
The invention aims at providing a thin film magnetic head, which solves these difficulties and enables high-density record and reproduction, and a production method thereof, and, a magnetic disk unit using this thin film magnetic head.